I. Technical Field
The present invention relates to a wheel bearing device and an axle module for supporting wheels to freely rotate the wheels relative to a vehicle body in a vehicle such as an automobile.
II. Description of the Related Art
Wheel bearing devices have evolved from a structure called first generation in which a double row roller bearing is independently used to second generation in which a vehicle body attachment flange is integrally provided in an outer member. Further, a third generation in which one inner raceway surface of the double row roller bearing is integrally formed with an outer periphery of a hub wheel integrally including a wheel attachment flange has been developed. Further, a fourth generation in which a constant-velocity universal joint is integrated with the hub wheel and the other inner raceway surface of the double row roller bearing is integrally formed with an outer periphery of an outer joint member constituting the constant-velocity universal joint has been developed.
For example, the wheel bearing device called third generation is described in JP 2004-340311 A. The wheel bearing device called third generation includes, as illustrated in FIG. 45, a hub wheel 152 including a flange 151 extending in an outer diameter direction, a constant-velocity universal joint 154 including an outer joint member 153 fixed to the hub wheel 152, and an outer member 155 disposed on an outer peripheral side of the hub wheel 152.
The constant-velocity universal joint 154 includes the outer joint member 153, an inner joint member 158 disposed in a cup-like section 157 of the outer joint member 153, balls 159 disposed between the inner joint member 158 and the outer joint member 153, and a cage 160 that retains the balls 159. Further, a spline section 161 is formed on an inner peripheral surface of a center hole of the inner joint member 158. An end spline section of a shaft (not shown) is inserted into the center hole, and thus the spline section 161 on the inner joint member 158 side and the spline section on the shaft side are engaged.
Further, the hub wheel 152 includes a cylindrical shaft section 163 and the flange 151. A short-cylindrical pilot section 165, on which a wheel and a brake rotor (not shown) are mounted, is protrudingly provided on an outer end surface 164 (end surface on an outboard side) of the flange 151. Note that, the pilot section 165 includes a large-diameter first section 165a and a small-diameter second section 165b. The brake rotor is externally fit in the first section 165a and the wheel is externally fit in the second section 165b. 
A small-diameter step section 166 is provided in an outer peripheral surface at an end on the cup-like section 157 side of the shaft section 163. An inner race 167 is fit in the small-diameter step section 166. A first inner raceway surface 168 is provided in the vicinity of a flange on an outer peripheral surface of the shaft section 163 of the hub wheel 152. A second inner raceway surface 169 is provided on an outer peripheral surface of the inner race 167. Further, a bolt inserting hole 162 is provided in the flange 151 of the hub wheel 152. A hub bolt for fixing the wheel and the brake rotor to the flange 151 is inserted into the bolt inserting hole 162.
In the outer member 155, outer raceway surfaces 170 and 171 in two rows are provided on an inner periphery thereof and a flange (vehicle body attachment flange) 182 is provided on an outer periphery thereof. The first outer raceway surface 170 of the outer member 155 and the first inner raceway surface 168 of the hub wheel 152 are opposed to each other. The second outer raceway surface 171 of the outer member 155 and the raceway surface 169 of the inner race 167 are opposed to each other. Rolling elements 172 are interposed between the second outer raceway surface 171 and the raceway surface 169. Further, the vehicle body attachment flange 182 is provided on the outer peripheral surface (outer diameter surface) of the outer member 155, the flange 182 being attached to a knuckle (not shown).
A shaft section 173 of the outer joint member 153 is inserted into the shaft section 163 of the hub wheel 152. In the shaft section 173, a screw section 174 is formed at an end of a reverse cup-like section thereof. A spline section 175 is formed between the screw section 174 and the cup-like section 157. Further, a spline section 176 is formed on an inner peripheral surface (inner diameter surface) of the shaft section 163 of the hub wheel 152. When the shaft section 173 is inserted into the shaft section 163 of the hub wheel 152, the spline section 175 on the shaft section 173 side and the spline section 176 on the hub wheel 152 side are engaged.
A nut member 177 is screwed onto the screw section 174 of the shaft section 173 projecting from the shaft section 163. Then, the hub wheel 152 and the outer joint member 153 are connected. In this case, an inner end surface (rear surface) 178 of the nut member 177 and an outer end surface 179 of the shaft section 163 come into contact with each other and an end surface 180 on a shaft section side of the cup-like section 157 and an outer end surface 181 of the inner race 167 come into contact with each other. In other words, when the nut member 177 is tightened, the hub wheel 152 is nipped by the nut member 177 and the cup-like section 157 through intermediation of the inner race 167.